The poet repeats the word "under" in these stanzas to establish the figurative meaning of the petals
Explanation:
"Night" is a representation of the detachment of H.D. from victorian style to get into modernism, every line where the rose loses its petals, and when it is described that they fall to the ground it represents how H.D. leaves behind the conventionalism of the old literary forms of victorian writers, the petals represent all the things that are no longer necessary.
The repetition emphasizes Johnson's belief in justice, and he guarantees to the American people that he will do everything in his power to ensure equal rights for all.